Recently, semiconductor devices such as a flash memory tend to be highly integrated. Accordingly, a pattern size has been significantly miniaturized. When forming such patterns, as one process of manufacture, a predetermined processing of oxidizing or nitriding on a substrate may be performed.
As a method of forming the patterns, there is a process of forming a groove between circuits and forming a seed film, a liner film or a wiring therein. This type of groove is configured to have a high aspect ratio, according to a recent miniaturization trend.
When forming the liner film and the like, it is required to form the film with a good step coverage, which has no variation in a film thickness and a film quality in an upper side surface, in a middle side surface, in a lower side surface, and in a bottom part of the groove. By forming the film with a good step coverage, it is possible to make properties of semiconductor devices in each groove uniform, thereby suppressing variations in the properties of semiconductor devices.
As a hardware structure approach for making the properties of semiconductor devices uniform, for example, there is a shower head structure of a single-wafer type apparatus, having gas dispersion holes formed above a substrate so that the gas is uniformly supplied.
Further, as a substrate processing method to make the properties of semiconductor devices uniform, for example, there is an alternate gas supply method in which at least two types of process gases are alternately supplied so that the processes gases react on a surface of a substrate. In the alternate gas supply method, in order to suppress respective gases from reacting in parts other than the substrate surface, remaining gases are removed by a purge gas while respective gases are supplied.
To further improve film properties, it may be considered to use the alternate gas supply method in an apparatus that employs the shower head structure. In this case, it may be considered to provide a respective buffer space or a respective gas supply path for each gas to prevent the mixture of the gases. However, in such a case, since the structure is complicated, a lot of care is required for maintenance and cost increases as well. Accordingly, it is practical to use a showerhead where supply systems of two types of gases and a purge gas are integrated into one buffer space.
However, when using the shower head including the common buffer space for two types of gases, the remaining gases may react with each other in the shower head so that adhered matters are deposited on an inner wall of the shower head. In order to avoid such a case, it is preferable to form an exhaust hole in the buffer chamber, through which atmosphere is exhausted such that the remaining gases in the buffer chamber are efficiently removed.
When using the shower head including the common buffer space for two types of gases, the apparatus is configured so that the two types of gases and the purge gas to be supplied to a process space are not diffused in a direction to the exhaust hole for exhausting the buffer space. For this configuration, for example, a gas guide configured to form a flow of gas is installed in the buffer chamber. It is preferable that the gas guide is, for example, provided between the exhaust hole for exhausting the buffer space and a supply hole configured to supply the two types of gases and the purge gas, and is installed radially toward a dispersion plate of the shower head.
In the case of the shower head having such complicated structure as discussed above, a gas may be collected or stagnant between components due to a problem of processing precision of components or a complexity of a components layout. Thus, byproducts or the like may adhere to corresponding portions. It is difficult for a cleaning gas to reach those portions where a gas is collected so that byproducts may remain thereon. Thus, it may be considered to disassemble the apparatus and then immerse the shower head in a cleaning solution or the like so as to be cleaned.
After cleaning the shower head, it is required to reduce, among residual components such as the cleaning solution, a different component from the process gas as much as possible, when assembling the apparatus again. This is because, the component different from the process gas may negatively affect subsequent processes. In general, before assembling the apparatus, such different component is removed through a baking process that requires time consumption so that a considerable down time may be consumed. Meanwhile, in order to more reliably remove the different component, a method of evacuating air with a pump or the like after assembling may be used. However, it is difficult to remove such component with a turbo molecular pump for vacuumization as an existing pump that is installed in a semiconductor manufacturing apparatus due to a structural problem. Further, a dry pump is not appropriate to remove the different component from the foregoing shower head structure because of its small exhaust power. As described above, it is required to capture the component different from the process gas within the shower head because this component is likely to negatively affect film characteristics.